Tank Base

ABSTRACT

A method for the construction of an improved tank base. A tank base is constructed for protection against accidental spills and/or leaks associated with a tank battery. The improved tank base comprises at least one part of a suitable substrate, which allows for the adhesion of an elastomer such as polyurea. Polyurea is preferably applied using a spray device which yields an average coverage of about 50-80 mils, and most preferably 60 mils. If more than one substrate is used, one or more substrates can be bound together with a fastening system. Once pressure is applied in the form of weight, the fastening system can be removed, resulting in an improved tank base having at least one seam and impervious to the fluid of the tank battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/106,778 filed Oct. 20, 2008, the technical disclosures of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a structural element that provides load bearing support and the method for the production of same. In particular, an encapsulated polystyrene structure serves as a load bearing material for use in protecting against accidental spills and leaks associated with any type of storage, tank, or vessel.

2. Description of Related Art

During the production of oil and gas from an underground well, it is common for water to be produced along with the oil or gas. This water, called “produced water,” is typically separated from the oil or gas at the well site and temporarily stored in an above-ground storage tank, or AST (or combination of ASTs). The produced water varies in quality from one well to the next, and it can have high quantities of minerals, salts, oil, gas, sand and other substances dissolved, mixed or suspended in it. Produced water with a high concentration of impurities can be corrosive to the walls and ancillary piping of an AST and it can be toxic to the environment. A vehicle with a large storage tank attached to it periodically travels to the well site and transfers the produced water from the AST to the storage tank or vessel on the vehicle.

FIG. 1 illustrates an AST 100 with an input stream 18 and an outlet stream 20. The flow rate of the outlet stream 20 is manipulated by way of a valve 22. The produced water travels from the underground hydrocarbon bearing formation 6, up the oil or gas well bore hole 4, into what is known as a “Christmas tree” 10, which is an assembly of valves, pipes and fittings used to control the flow or oil and gas from a well. The water separating section 14 of the Christmas tree 10 directs the produced water to the AST 100. Other separating sections 12 direct the oil or gas into a pipeline 16, which transports the oil or gas to other locations for further processing or sale. A manway entrance 350 enables a technician to view the interior of the storage tank and inspect the tank for leaks, while the plumbing connections 380 to the storage cavity of said tank enable pumping of the contents therein. As seen in the side view in FIG. 1, the manway 350 extends below the bottom of the tank.

Accidental spills or leaks can occur for a variety of reasons. For example, FIG. 2 illustrates the AST 100 of FIG. 1 after the produced water has corroded the walls of the tank, creating a hole 26 in the wall of the AST. The hole 26 allows the produced water to spill or leak out of the AST 100 and onto the ground 2. In order to protect the environment from an accidental discharge such as the one illustrated in FIG. 2, approved ASTs are typically required to retain any and all fluid such that contaminate are prevented from entering the environment surrounding the well site. Fluid accumulates within ASTs and secondary containment systems from multiple sources including natural and accidental leaks or spills. ASTs usually need to have the capacity and strength to hold at least 150% of the volume of the AST, or for an array of ASTs, 150% of the largest AST in the array.

Currently, protection for the tank, soil and equipment in the containment of the top soil involves the use of a grade band of metal filled with pea gravel below the containment tank. The grade band metal is typically bolted together to form a base greater than the diameter of the containment tank it supports. The diameter of the support structure (base and pea gravel) is typically 3″ to 6″ greater than that of the AST being supported and allows for the AST to sit approximately 3″ to 6″ in height off of the floor of a secondary containment area. This allows the AST or containment tank to be at a level greater than the ground level and aids in the slow deterioration of the tank due to any standing fluid within the secondary tank area, whether the fluid is natural (such as rainwater) or accidental (spills or leaks). The pea gravel currently used is naturally porous and allows for the absorption for any number of contaminants (i.e., oil, salts, acids, etc.) that come into contact with the gravel, causing permanent contamination, which still tends to spill out of the gravel upon oversaturation. Attempts to treat or wash out the contaminants are costly, difficult, and to-date, ineffective.

Consequently, a need exists for a more efficient, effective, and convenient method for building an improved tank base to provide for safer environment and green waste. There is a need for an improved tank base, capable of being steam cleaned of any contaminants to provide more environmentally friendly standards while maintaining other advantages of a tank base and reducing costs associated with maintenance or replacement of failing tanks. There is also a need for a tank base that provides for a more efficient and cost-effective means of the shipping, transporting, and installation into customer sites. Further, there is a need for a method which keeps out moisture, preventing the proliferation of bacteria which often causes erosion of tanks from the inside out.

SUMMARY OF THE INVENTION

The present invention provides a method for the encapsulation of a core material, which allows for the adhesion of an elastomer such as polyurea. In one embodiment, at least one part of a substrate such as expanded polystyrene (EPS) is designed or shaped and subsequently coated with polyurea for protection and strength. Preferably, the foam material comprises a density of at least two pounds per cubic foot of foam weight with an average coverage of about 50-80 mils and most preferably about 60 mils polyurea. Other suitable substrates (including without limitation wood, metal, concrete, paper fiber, fiberglass, fiber board, and gravel) allow for the adhesion of polyurea, which is preferably applied using a spray device. This allows for the protection of an above-ground storage tank (AST) system in addition to a more conveniently portable installation.

In a second embodiment, more than one part of a substrate is shaped as desired or needed to fit beneath a tank. Each substrate is individually coated with the polyurea and the coated materials are then fastened together around the outside circumferential periphery of the base and held together under the weight of an AST. The materials comprise at least one seam to allow for moisture to pass through such that no corrosion of the tank is experienced as a result of any standing fluid from accidental spillage or natural rainwater. Once pressure is applied in the form of weight, the fastener can be removed, resulting in an improved tank base having at least one seam and impervious to the fluid of the tank battery or within a secondary containment system. The polyurea-covered EPS is biodegradable and allows for steam cleaning to be rid of contaminating hydrocarbons and green waste disposal, if necessary.

Other aspects, embodiments and features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. The accompanying figures are schematic and are not intended to be drawn to scale. In the figures, each identical or substantially similar component that is illustrated in various figures is represented by a single numeral or notation. For purposes of clarity, not every component is labeled in every figure. Nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is an illustration of a prior art above ground storage tank at a well site.

FIG. 2 is an illustration of a prior art above ground storage tank with a hole in its wall.

FIG. 3 is an illustration of above ground storage tank situated over a tank base of the present invention.

FIG. 4 is an illustration of top perspective view of one embodiment of the tank base of the present invention.

FIG. 5 is an illustration of a side perspective view of the embodiment of the tank base of the present invention seen in FIG. 4.

FIG. 6 is an illustration of a side perspective view of an alternate embodiment of the tank base of the present invention.

FIG. 7 depicts a top perspective view of an alternate embodiment of the tank base of the present invention.

FIG. 8 depicts the side view of the alternate embodiment of the tank base of the present invention illustrated in FIG. 7.

FIG. 9 depicts an alternate embodiment of the tank base of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention involves an improved method for the construction of a tank base for use in a secondary containment area, storage facilities or any type of vessel. While the tank base of the present invention is described in terms of a secondary containment for a varying sizes of an AST, one skilled in the art, armed with this disclosure, will recognize that the present method and its resulting tank base is applicable to any number of secondary containment systems and vessel storage areas. Thus, while FIG. 1 depicts a cylindrical AST with its axis oriented perpendicular to the ground 2, one skilled in the art, armed with this disclosure, will recognize that the claimed invention works equally well within secondary containment systems of varying orientation, shape and positions relative to the ground or environment being protected. Further, as will be described below, the tank base of the present invention can be modified or custom built to accommodate any size and shape desired.

The exterior bottom portion of an AST is particularly susceptible to damage resulting from standing fluid when the AST is sitting directly on the floor of a secondary containment area. As described above, current methods of resolving this problem involves the use of a large tank base having portions bolted together and filled with pea gravel, which permanently absorbs contaminants. Current methods are labor intensive and require multiple parties to construct and supply the tank base.

FIG. 3 illustrates an AST 100 situated over the center portion of a tank base 300 of the present invention. As described above, moisture from standing water around the edges of a tank pose a problem for the maintenance of a tank 100 and contamination of the soil beneath the tank. The manway entrance 350 is illustrated in FIG. 3, depicting that portion of the tank to which access is granted for maintaining the tank, and is shown to extend now to the top of the tank base of the present invention. Thus, the containment base allows the tank 100 and plumbing 380 to be situated higher up from the ground, providing easier access through the manway 350. Preferably, any flat portion on the tank base is aligned with the manway entrance 350 to allow for ease of entry. In the embodiment seen in FIGS. 3 and 4, the tank base comprises three parts 320, 340 and 360 and two seams 310 in between each piece; however, as few seams as possible are preferable and if desired, one solid base with no seams is also possible. For ease of transfer and construction, the base is typically comprised of at least two parts or substrates positioned adjacent and secured to one another, creating an outer periphery around which a fastening system is employed to bind the substrates together.

As used herein, the term “suitable substrate” is used synonymously with “substrate” and is meant to include without limitation, concrete, metal, EPS, wood, concrete, paper fiber, fiberglass, fiber board, and gravel or any other substrate appropriate for the adhesion of a polyurea elastomer coating. Polyurea is an elastomer derived from the reaction between an isocyanate component and a resin blend component. Polyurea suitable for the present invention is available from Sherwin Williams under the name ENVIROPLASTIC® AR200HD or Versaflex under the name FSS 50DM. Currently, landfills and dike systems utilize secondary containments comprising EPS encapsulated with earth. Without being bounded by theory, it is believed that the present invention provides an improved tank base in part due to the high compressive strength of EPS in combination with the high adhesion rate and strength of polyurea, which helps encapsulate the polystyrene and keeps it from flaking off and failing under the weight of a the tank. While Applicants describe the present invention in terms of EPS due to its environmentally friendly nature and powerful design elements, other substrates having a compressive strength are also possible. EPS is 100% recyclable and in some parts of the world is currently already being recycled at higher levels than either glass or aluminum. Used polystyrene is biodegradable and has no impact on the environment even in landfill sites or in incinerators, nor does it contain substances that could pollute the air or soil. Further, the manufacture of EPS solutions does not release hydrosoluable substances that could contaminate ground water supplies. Suitable EPS materials are commercially available.

The method by which the present invention is constructed will now be explained. The first step is to design the substrates to be encapsulated as support for a tank battery or in a secondary containment system. As used herein, the designing step is meant to include the cutting, shaping or forming of the substrates into custom shapes or sizes to be used with varying sizes of tanks or within a given containment area. At least one substrate is designed to customer requirements and according to the size and diameter required for the tank battery. As depicted best in FIG. 4, the measurements x and y can vary to any number depending on the secondary containment system or AST to be supported. In test runs, a tank weighing approximately 110 thousand pounds called for EPS having a foam density of 2 pounds per cubic foot of foam weight, ranging from about 3 to 12 inches in height. In addition, the overall diameter of one or more substrates when lying side by side was about 10 to 18 feet in diameter during successful test runs. One skilled in the art, armed with this disclosure, will recognize that one or more substrates can be used in accordance with the present invention. For example, a solid base can be used and alternatively, two solid halves of a base can be placed adjacent to one another and tied together to form a base with at least one seam, which allows for the passage of water to prevent corrosion of the tank. Further, it can be recognized that the foam density can be increased to accommodate more than 100 thousand pounds and to provide the load bearing support needed for the present invention.

The next step involves independently encapsulating each substrate with a polyurea elastomer. Once formed to the necessary specifications or sizes, each substrate is individually coated with polyurea for protection and strength. Preferably, the application is performed using specialized equipment that uses high temperatures and high pressures for mixing directly in an impingement mix spray gun. In one embodiment, the polyurea coating is independently applied using a spray device operating at a temperature of approximately 165 degrees Fahrenheit and a pressure of approximately 1800 pounds per square inch (psi) to encapsulate each substrate. The average coverage of polyurea will be about 50-80 mils, and more preferably about 60 mils coverage. However, one skilled in the art, armed with this disclosure, will recognize that other coverages are also possible depending on the desired compressive strength of the tank base and the required application.

The third step in creating the improved tank containment base of the present invention involves binding the coated substrates together at the well site. The substrates are positioned adjacent to one another and bound together with a fastening system. Simultaneously or subsequently, the substrates can be aligned appropriately as discussed above, with the manway entrance aligned with a flat section of the tank base. When aligning the base, the plumbing features of the tank is also be taken into account such that a flat edge is aligned with the manway entrance and plumbing. In test runs, a 45 foot nylon strap with a cam buckle was used to secure the coated substrates around the outer periphery of the edges and hold the pieces together until the pressure from the weight of the tank is applied. Once properly aligned, the AST is placed on the tank base and the fastening system may be removed, if desired, or may stay in place as the discretion of the owner. The polyurea coating of the tank base is impervious to the fluid of the AST and will not allow for the contamination of the substrate or deterioration of the AST. The coating also allows for ease of cleaning as the material can now be steamed to extract out any hydrocarbon resins. This also allows for the environmentally safe disposal of the base if necessary.

As seen in FIGS. 4 through 9, the independent nature of the substrates forms seams 310 in between the substrates. It is desirable to have as few seams as possible. FIGS. 5 and 6 illustrate side views of the bases and the corresponding seams possible with the present invention. Straight seams depicted in FIG. 5 allow for any moisture from rainwater, for example, to pass through so as to prevent corrosion of the tank from standing water effects. Interlocking seams seen in FIG. 6 also allow for moisture to seep away from the bottom of the tank but also allow for another embodiment in which to piece or hold together the substrates. It is noteworthy that the secondary containment system should be as level as possible with only a slight gradient to allow fluid to “pool” at one end for removal (i.e. pumping) requirements. Alternatively, FIGS. 7 and 8 depict an alternate embodiment wherein the center substrate portion 340 is slightly raised above the height of side substrate portions 320 and 360. This allows for pooling to occur along either side of the base, rather than in the center of the tank. FIG. 7 further depicts the use of funnels 370 to aid in dispersing fluids away from underneath the tank for release into specific areas within the secondary containment system. FIG. 8 depicts another embodiment of the present invention, comprising a different shape.

While the invention has been particularly described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, one skilled in the art, armed with this disclosure, will recognize that a variety of shapes and dimensions are possible with the present invention and can be tailor made according to the needs of a secondary containment system and/or the weight to be applied to the base. Further, the invention can be used in and around any area having highly corrosive or hazardous material and with any vessel or storage container. The terms and expressions employed herein have been used as terms of description and not of limitation; and thus, there is no intent of excluding equivalents, but on the contrary it is intended to cover any and all equivalents that may be employed without departing from the spirit and scope of the invention. 

1. A method for constructing an improved tank base for use in a tank battery comprising the steps of: a) designing at least one substrate, wherein said at least one substrate comprises a material capable of adhesion with an elastomer coating; and b) coating the at least one substrate with said elastomer, thereby forming at least one coated substrate.
 2. The method of claim 1, wherein said designing step a) is designed to fit within a secondary containment system for an above ground storage tank.
 3. The method of claim 1, wherein said designing step a) is designed to fit underneath a tank battery.
 4. The method of claim 1, wherein said designing step a) utilizes a substrate made of expanded polystyrene.
 5. The method of claim 1, wherein said step b) is performed with a polyurea elastomer.
 6. The method of claim 1, wherein said step b) is performed until the substrate coating is at least 50 mils thick.
 7. The method of claim 1 further comprising the steps of: c) aligning the at least one coated substrate with a tank battery; and d) positioning an above-ground storage tank over the at least one coated substrate wherein said at least one coated substrate forms the tank base.
 8. The method of claim 1 further comprising the step of: c) aligning the at least one coated substrate adjacent to a second coated substrate, wherein said second coated substrate is made by the same method as said at least one coated substrate such that at least one seam is formed in between the two coated substrates and an outer periphery is formed around the edges of the aligned two coated substrates.
 9. The method of claim 8 further comprising the step of d) securing each of the two coated substrates together around the outer periphery to form the tank base.
 10. The method of claim 9 further comprising the step of e) positioning an above-ground storage tank over said tank base.
 11. The method of claim 9, wherein said securing step d) further comprises using a strap around the outer periphery of said two coated substrates.
 12. The method of claim 1, wherein said coating step b) is performed using a spray device that operates at a temperature of about 165 degrees Fahrenheit and a pressure of about 1800 pounds per square inch.
 13. The method of claim 8, further comprising the steps of: d) aligning a third coated substrate, said third coated substrate made by the same method as said at least one coated substrate, with the at least one coated substrate and the second coated substrate such that at least two seams are formed in between the three coated substrates and an outer periphery is formed around the edges of the aligned three coated substrates.
 14. The method of claim 13, further comprising the step of e) securing each of the three coated substrates together to form the tank base.
 15. The method of claim 13, wherein further coated substrates, made by the same method as said at least one coated substrate, are aligned adjacent to and secured to one another to form the tank base.
 16. An improved lank base comprising a substrate covered with an elastomer coating to form an impenetrable and biodegradable load bearing support for an above-ground storage tank.
 17. The improved tank base of claim 16, wherein said elastomer is comprised of polyurea.
 18. The improved tank base of claim 16, wherein said substrate is comprised of polystyrene.
 19. The improved tank base of claim 16, wherein said substrate has a foam density of 2 pounds per cubic foot of foam weight.
 20. The improved tank base of claim 16, wherein tank base has a height ranging from three to twelve inches.
 21. The improved tank base of claim 16, wherein said elastomer coating is at least 50 mils thick. 